Method for producing a corrosion-inhibiting coating on an implant made of a bio-corrodible magnesium alloy and implant produced according to the method

Abstract

A method for producing a corrosion-inhibiting coating on an implant made of a biocorrodible magnesium alloy, the method comprising providing the implant; and treating the implant surface using an aqueous or alcoholic conversion solution containing one or more ions selected from the group consisting of K + , Na + , NH 4 + , Ca 2+ , Mg 2+ , Zn 2+ , Ti 4+ , Zr 4+ , Ce 3+ , Ce 4+ , PO 4 3− , HPO 4 2− , H 2 PO 4 − , OH − , B 3 3− , B 4 O 7 2− , SiO 3 2− , MnO 4 2− , MnO 4 − , VO 3 − , WO 4 2− , MoO 4 2− , TiO 3 2− , Se 2− , ZrO 3 2− , and NbO 4 − , wherein the concentration of the ion or ions is in the range of from 0.01 mol/l to 2 mol/l. An implant produced by this method is also disclosed.

1 . A method for producing a corrosion-inhibiting coating on an implant having a surface and made of a biocorrodible magnesium alloy, the method comprising:
 a) treating the implant surface using an aqueous or alcoholic conversion solution comprising one or more ions selected from the group consisting of K + , Na + , NH 4   + , Ca 2+ , Mg 2+ , Zn 2+ , Ti 4+ , Zr 4+ , Ce 3 + , Ce 4+ , PO 4   3− , HPO 4   2− , H 2 PO 4   − , OH − , BO 3   3− , B 4 O 7   2− , SiO 3   2− , MnO 4   2−, MnO   4   − , VO 3   − , WO 4   2− , MoO 4   2− , TiO 3   2− , Se 2− , ZrO 3   2− , and NbO 4   − ,   wherein the concentration of the ion or the ions is in the range of from 0.01 mol/l to 2 mol/l, respectively.   
   
   
       2 . The method of  claim 1 , wherein the conversion solution contains OH— ions and one or more ions selected from the group consisting of K + , Na + , NH 4   + , Ca 2+ , Mg 2+ , Zn 2+ , Ti 4+ , Zr 4+ , Ce 3+ , Ce 4+ , PO 4   3− , HPO 4   2− , H 2 PO 4   − , OH − , BO 3   3− , B 4 O 7   2− , SiO 3   2− , MnO 4   2− , MnO 4   − , VO 3   − , WO 4   2− , MoO 4   2− , TiO 3   2− , Se 2− , ZrO 3   2− , and NbO 4   − . 
   
   
       3 . The method of  claim 1 , wherein the conversion solution contains one or more cations selected from the group consisting of K + , Na + , NH 4   + , Ca 2+ , and Mg 2+ . 
   
   
       4 . The method of  claim 1 , wherein the conversion solution contains one or more anions selected from the group consisting of MnO 4   2− , MnO 4   − , VO 3   − , WO 4   2− , MoO 4   2− , TiO 3   2− , ZrO 3   2− , and NbO 4   − . 
   
   
       5 . The method of  claim 1 , wherein the conversion solution comprises:
 (i) OH − ;   (ii) one or more anions selected from the group consisting of PO 4   3− , H 2 PO 4   − , HPO 4   2− , BO 3   3− , B 4 O 7   2− , and SiO 3   2−  to form a cover layer;   (iii) one or more cations selected from the group consisting of K + , Na + , NH 4   + , Ca 2+ , and Mg 2+ ; and   (iv) one or more anions selected from the group consisting of MnO 4   2− , MnO 4   − , VO 3   − , WO 4   2− , MoO 4   2− , TiO 3   2− , ZrO 3   2− , and NbO 4   −  as oxidant.   
   
   
       6 . The method of  claim 1 , wherein the treatment in step a) is performed by anodic oxidation with application of a voltage to the implant. 
   
   
       7 . The method of  claim 6 , wherein the conversion solution used for anodic oxidation contains one or more ions selected from the group consisting of NH 4   + , PO 4   3− , and BO 3   3−  and wherein the anodic oxidation is performed with external power source under plasma discharge. 
   
   
       8 . The method of  claim 7 , wherein the conversion solution contains one or more ions selected from the group consisting of K + , Na + , NH 4   + , MnO 4   3− , and VO 3   − . 
   
   
       9 . The method of  claim 1 , wherein the treatment in step a) comprises contacting the implant with a noble metal selected from the group consisting of Pt, Au, Rh, and Ru. 
   
   
       10 . An implant having a corrosion-inhibiting coating provided by a method, comprising:
 a) treating the implant surface using an aqueous or alcoholic conversion solution containing one or more ions selected from the group consisting of K + , Na + , NH 4   + , Ca 2+ , Mg 2+ , Zn 2+ , Ti 4+ , Zr 4+ , Ce 3+ , Ce 4+ , PO 4   3− , HPO 4   2 − , H 2 PO 4   − , OH − , BO 3   3− , B 4 O 7   2− , SiO 3   2− , MnO 4   2− , MnO 4   − , VO 3   − , WO 4   2− , MoO 4   2− , TiO 3   2− , Se 2− , ZrO 3   2− , and NbO 4   − ,   wherein the concentration of the ion or the ions is in the range of from 0.01 mol/l to 2 mol/l, respectively.   
   
   
       11 . The implant of  claim 10 , wherein the corrosion-inhibiting coating has a layer thickness in the range of from 300 nm to 20 μm. 
   
   
       12 . The method of  claim 2 , wherein the conversion solution contains one or more cations selected from the group consisting of K + , Na + , NH 4   + , Ca 2+ , and Mg 2+ . 
   
   
       13 . The method of  claim 1 , wherein the treatment in step a) is performed by immersing the implant in the conversion solution. 
   
   
       14 . The implant of  claim 10 , wherein the implant is a stent.